Optical mechanism which allows play between transmission members for moving optical components

Abstract

A lens barrel has a focusing operation and a zooming operation which are carried out with only one driving source which is installed outside the lens barrel so as to realize a most suitable resolution for each of the operations. A rotary cylinder which supports a zooming frame which is axially movably therein, is connected to a linear-moving cylinder with a bayonet, which is axially movably supported inside a fixed cylinder. A focus rotation transmission key of a driving cylinder drives a lens frame which engages the zooming frame by a connecting helicoid. A zooming rotation transmission key of the driving cylinder engages an edge surface, forming a rotation transmission groove, of the rotary cylinder, with a play range. Upon rotation of the driving cylinder, only the lens frame is rotated to operate a focusing operation within the play range; however, the rotary cylinder is rotated to operate a zooming operation when the key contacts the edge surface of the rotary cylinder.

What is claimed is: 
     
       1. A zoom lens barrel, comprising: a zoom driving system comprising a focus driving system, the focus driving system comprising a first lens group, said zoom driving system further comprising a second lens group;   a first transmission mechanism for transmitting a driving force from an outside driving source to the focus driving system; and   a second transmission mechanism, which allows a predetermined play between the zoom driving system and the first transmission mechanism, for transmitting the driving force of the first transmission mechanism to the second lens group when the play is absorbed between the first transmission mechanism and the zoom driving system,   wherein the focus driving system as a whole and the second lens group move relative to each other for a zooming operation,   wherein only the focus driving system is driven by the driving force of the first transmission mechanism when the play is not absorbed between the first transmission mechanism and the zoom driving system, so that the first lens group is moved for focusing operation, and   wherein the zoom driving system is driven by the driving force of the first transmission mechanism when the play is absorbed between the first transmission mechanism and the zoom driving system, so that the focus driving system as a whole and the second lens group are moved for the zooming operation.   
     
     
       2. The zoom lens barrel as claimed in claim 1, wherein the focus driving system further comprises: a lens frame holding the first lens group therein; and   a cylindrical zooming frame holding the lens frame movably therein,   wherein the lens frame is rotated by the first transmission mechanism,   wherein the cylindrical zooming frame is moved during the zooming operation,   wherein the lens frame and the cylindrical zooming frame engage each other with a helicoid connection, and   wherein the zooming frame of the focus driving system is rotated in a same rotational direction and with a same rotational amount as the lens frame thereof which is rotated by the first transmission mechanism when the driving force is transmitted from the first transmission mechanism to the zoom driving system via the second transmission mechanism.   
     
     
       3. The zoom lens barrel as claimed in claim 1, wherein the second lens group is provided between an object to be photographed and the first lens group. 
     
     
       4. The zoom lens barrel as claimed in claim 1, which further comprises a shutter mechanism between the first lens group and the second lens group. 
     
     
       5. The zoom lens barrel as claimed in claim 1, wherein the zoom driving system further comprises a finder driving transmission mechanism for transmitting the driving force from the first transmission mechanism to a finder mechanism when the zoom driving system is driven by the first transmission mechanism. 
     
     
       6. An optical mechanism, comprising: a motor;   a first moving member holding a first optical component;   a second moving member holding a second optical component;   a first transmission member driven by a driving force from the motor;   a second transmission member engaging the first transmission member with a predetermined play between the first transmission member and the second transmission member;   a first moving mechanism for moving the first moving member along an optical axis by a relative movement between the first transmission member and the second transmission member; and   a second moving mechanism for moving the second moving member along the optical axis when the play does not exist between the first transmission member and the second transmission member, so that the second transmission member is driven by the first transmission member.   
     
     
       7. The optical mechanism as claimed in claim 6, wherein the first moving mechanism is moved together with the first moving member by the second moving mechanism. 
     
     
       8. The optical mechanism as claimed in claim 6, wherein a displacement of the first moving member along the optical axis by the first moving mechanism for a constant rotational amount of the motor is different from a displacement of the first moving member along the optical axis by the second moving mechanism for the constant rotational amount of the motor. 
     
     
       9. A zoom lens barrel, comprising: a zoom driving system comprising a focus driving system, the focus driving system comprising a first lens group, said zoom driving system further comprising a second lens group;   a first transmission mechanism for transmitting a driving force from an outside driving source to the focus driving system during a focusing operation and a zooming operation; and   a second transmission mechanism, which allows a predetermined play between the second lens group and the first transmission mechanism, for transmitting the driving force of the first transmission mechanism to the second lens group when the play is absorbed between the second lens group and the first transmission mechanism.   
     
     
       10. A zoom lens barrel, comprising: a zoom driving system comprising a focus driving system, the focus driving system comprising a first lens group, said zoom driving system further comprising a second lens group;   a first transmission mechanism for transmitting a driving force from an outside driving source to the focus driving system;   a predetermined play between the zoom driving system and the first transmission mechanism; and   a second transmission mechanism for transmitting the driving force of the first transmission mechanism to the zoom driving system when the play is absorbed between the zoom driving system and the first transmission mechanism.   
     
     
       11. A zoom lens barrel, comprising: a zoom driving system comprising a focus driving system, the focus driving system comprising a first lens group, said zoom driving system further comprising a second lens group;   a first transmission mechanism for transmitting a driving force from an outside driving source to the focus driving system;   a second transmission mechanism, which allows a predetermined play between the zoom driving system and the first transmission mechanism, for transmitting the driving force of the first transmission mechanism to the zoom driving system when the play is absorbed between the zoom driving system and the first transmission mechanism; and   a finder driving transmission mechanism for transmitting the driving force from the first transmission mechanism to a finder mechanism,   wherein only the focus driving system is driven by the driving force of the first transmission mechanism when the play is not absorbed between the zoom driving system and the first transmission mechanism, and   wherein the zoom driving system and the finder driving transmission mechanism are driven by the driving force of the first transmission mechanism when the play is absorbed between the zoom driving system and the first transmission mechanism.   
     
     
       12. A zoom lens barrel, comprising: a zoom driving system comprising a focus driving system, the focus driving system comprising a first lens group, said zoom driving system further comprising a second lens group;   a first transmission mechanism for transmitting a driving force from an outside driving source to the focus driving system;   a second transmission mechanism, which allows a predetermined play between the zoom driving system and the first transmission mechanism, for transmitting the driving force of the first transmission mechanism to the zoom driving system when the play is absorbed between the zoom driving system and the first transmission mechanism; and   a third transmission mechanism, which allows a predetermined play corresponding to the play of the second transmission mechanism, for transmitting the driving force from the first transmission mechanism to a finder driving mechanism,   wherein only the focus driving system is driven by the driving force of the first transmission mechanism when the play is not absorbed between the zoom driving system and the first transmission mechanism, and   wherein the third transmission mechanism is driven by the driving force of the first transmission mechanism when the play is absorbed between the finder driving mechanism and the first transmission mechanism.